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One Health, as a multi-disciplinary approach, considers animal, human, and environmental health. Serbia continuously records high rates of antimicrobial resistance, with a knowledge gap on practices regarding veterinary antibiotic use, as no standardized data regarding veterinary consumption of antibiotics that would allow for temporal or spatial comparison are available in Serbia. This study aimed to describe the sales of veterinary antibiotics in Serbia. Aggregated wholesale data on veterinary drug sales were retrieved from the annual reports available from the Medicines and Medical Devices Agency of the Republic of Serbia for a period between 2017 and 2020. Veterinary use was analyzed using standard European Medicines Agency proposed methodology and expressed in milligrams of active substance per population correction unit (mg/PCU). Overall, there has been a 13% increase in aggregated sales, in mg/PCU, of antibiotic veterinary medicinal products (VMPs) for food-producing animals in Serbia between 2017 and 2020. With sales of around 110 mg/PCU in 2020, Serbia would have ranked ninth in Europe. In 2020, the overall highest-selling antibiotic classes were penicillins (27.62 mg/PCU), tetracyclines (27.54 mg/PCU), and aminoglycosides (12.8 mg/PCU), accounting for 61.9% of the total sales of antibiotic VMPs for food-producing animals, in mg/PCU. An increase in the use of macrolides and lincosamides and a decrease in the use of penicillins and the group classified as “other antibacterials” was noted. The current study identified an increase in the sales of veterinary antibiotics in Serbia and pointed out several potential problem areas.

The use of organic ingredients as a source of protein in aquaculture diets has gained significant attention due to the growing demand for organic seafood products. This study aimed to evaluate the potential for the use of organic ingredients as protein sources in the diet of juvenile organic seabass (Dicentrarchus labrax). A total of 486 juvenile seabass with an average weight of 90 g were fed six diets containing varied organic proteins. The control group (CON) was fed a diet with conventional fishmeal from sustainable fisheries as the primary protein source. The other five groups were fed diets with different compositions: organic Iberian pig meal byproduct (IB diet), a combination of organic Iberian pig meal byproduct and insect meal (IB-IN diet), a mix of organic Iberian pig meal byproduct and organic rainbow trout meal byproduct (IB-TR diet), a blend of organic rainbow trout meal byproduct and insect meal (TR-IN), and a mixed diet containing all of these protein sources (MIX diet). Over a 125-day feeding trial, growth performance, feed utilisation, feed digestibility, and histological parameters were assessed. The results showed that the fish fed the control diet had the highest final weight and specific growth rate, followed by the fish fed the TR-IN and IB-TR diets. The IB-TR diet had the highest apparent digestibility coefficients (ADCs) for protein, while the TR-IN diet had the lowest. Histological analysis revealed that fish fed the control diet had the largest nucleus diameter and hepatocyte diameter. Use of IN seems to penalise performance in several ways. Fish fed diets containing insect meal grew less, and those diets had lower digestibility. Fish fed the TR and IB diets grew at rates near that of the control, and the feed had acceptable digestibility.

The fishmeal replacement by vegetable meals or other alternative sources, without affecting fish performance and productivity, is one of the principal challenges in aquaculture. The use of hydrolyzed porcine mucosa (HPM) and nucleotide (NT) concentrates, as feed additives in gilthead seabream (Sparus aurata L.) non-fishmeal diets was assessed in order to determine the possible effects on growth, feed efficiency, protein digestion, and gut histology when these were included in a plant-based diet (HPM 1% and 2%, P1 and P2; NT 250 and 500 ppm, N250 and N500), in comparison with two control diets, AA0 (100% plant-protein-based diet) and FM100 (100% fishmeal-protein-based diet). Diets were assayed in triplicate and the growth assay lasted 134 days. Results showed a significant improvement in all groups in terms of final weight and specific growth rate in comparison with the AA0 group. An improvement in the feed conversion ratio and the protein efficiency ratio was also observed when the additives were included in lower percentages (P1 and N250) compared to the FM100 group. Significant differences were found in hepatosomatic index, villi thickness, and goblet cells. Thus, the inclusion of NT and HPM was tested as beneficial for the improvement of efficiency of plant feed in seabream.

The aquaculture of carnivorous fish is in continuous expansion, which leads to the need to reduce the dependence on fishmeal (FM). Plant proteins (PP) represent a suitable protein alternative to FM and are increasingly used in fish feed. However, PP may lead to stunted growth and enteritis. In the current study, the effect of high FM substitution by PP sources on the growth, mortality and intestinal health of rainbow trout (Oncorhynchus mykiss) was evaluated in terms of the histological intestine parameters and expression of genes related to inflammation (IL-1β, IL-8 and TGF-β) and immune responses (Transferrin, IgT and IFN-γ). The results show that a total substitution registered lower growth and survival rates, probably due to a disruption to the animal’s health. Confirming this hypothesis, fish fed FM0 showed histological changes in the intestine and gene changes related to inflammatory responses, which in the long-term could have triggered an immunosuppression. The FM10 diet presented not only a similar expression to FM20 (control diet), but also similar growth and survival. Therefore, 90% of FM substitution was demonstrated as being feasible in this species using a PP blend of wheat gluten (WG) and soybean meal (SBM) as a protein source.

This study was conducted to evaluate the apparent availability and P and N excretion in rainbow trout (Oncorhynchus mykiss) using different inorganic phosphorus sources. With this goal, fish (153 ± 14.1 g) fed four inorganic P sources were assayed: monoammonium phosphate (MAP, NH4H2PO4), monosodium/monocalcium phosphate (SCP-2%, AQphos+, NaH2PO4/Ca(H2PO4)2·H2O in proportion 12/88), monosodium/monocalcium phosphate (SCP-5%, NaH2PO4/Ca(H2PO4)2·H2O in proportion 30/70) and monocalcium phosphate (MCP, Ca(H2PO4)2·H2O). Phosphorus (P) digestibility, in diets that included MAP and SCP-2% as inorganic phosphorus sources, were significantly higher than for SCP-5% and MCP sources. In relation to the P excretion pattern, independent of the diet, a peak at 6 h after feeding was registered, but at different levels depending on inorganic P sources. Fish fed an MAP diet excreted a higher amount of dissolved P in comparison with the rest of the inorganic P sources, although the total P losses were lower in MAP and SCP-2% (33.02% and 28.13, respectively) than in SCP-5% and MCP sources (43.35% and 47.83, respectively). Nitrogen (N) excretion was also studied, and the fish fed an SCP-5% diet provided lower values (15.8%) than MAP (28.0%). When N total wastes were calculated, SCP-2% and SCP-5% showed the lowest values (31.54 and 28.25%, respectively). In conclusion, based on P and N digestibility and excretion, the SCP-2% diet showed the best results from a nutritional and environmental point of view.

The meagre is a carnivorous species and might be a suitable candidate species for the diversification of aquaculture in the Mediterranean region. This is based on its high growth and flesh quality. Nevertheless, there is little information available about its growth rates and nutrient requirements. The objective of this study was to determine the protein and energy requirements of juvenile meagre (Argyrosomus regius). Two trials for different weights of 53 and 188 g were conducted with rations from starvation to apparent satiation with the scope of studying its nutritional needs. In the first trial, the initial mean body weight of the fish was 53 g, and they were fed at feeding rates, measured as a percentage of the body weight, of 0, 0.75, 1.5, 2.5, 3.5, and 4.5%, with two replicates per treatment. In a second trial, another group with approximately 188 g of initial body weight was fed at feeding rates of 0, 0.5, 1.5, and 2.5%, with two replicates per treatment. The optimum thermal growth coefficient was obtained with a feed intake of 2.2% day−1 in trial A and 1.73% day−1 in trial B. The digestible protein (DP) intake for maintenance was determined as 0.57 g kg−0.7 day−1, the DP intake for maximum growth was 6.0 g kg−0.7 day−1, and the point for maximum efficiency in protein retention was 1.8 g kg−0.7 day−1. The requirement for digestible energy (DE) intake for maintenance was recorded at 25.4 kJ kg−0.82 day−1, the DE intake to maximize growth was 365 kJ kg−0.82 day−1, and the point for maximum efficiency in energy retention occurs with a digestible energy intake of 93 kJ kg−0.82 day−1. The requirements and retention efficiency of protein and energy in Argyrosomus regius tend to be within the range other fish species. The maintenance needs are in agreement with species with low voluntary activity and growth requirements in agreement with fast-growth species.

The study aimed to evaluate how replacing different proportions of fish oil (FO) with vegetable oils (VO) in the diet of Mediterranean yellowtail, Seriola dumerili (Risso, 1810), affects the fatty acids (FA) signature, i.e.; overall FA profile, in different tissues. A total of 225 Mediterranean yellowtail juveniles (initial live weight: 176 ± 3.62 g) were fed for 109 days with one of three diets: A control diet (FO 100), with FO as the only lipid source, or diets with 75% and 100% of FO replaced with a VO mixture. At the end of the feeding trial, the brains, muscles, livers, and visceral fat were sampled in four fish per tank (12 per treatment), and their fat were extracted and used for FA analysis. The FA signatures of red and white muscle, liver, and visceral fat tissues changed when the dietary FA source changed, whereas FA signatures in the brain were rather robust to such dietary changes. These new insights might help evaluate whether key physiological functions are preserved when fish are fed diets with low FO levels, as well as define the dietary FA requirements of Mediterranean yellowtail to improve the sustainability of the production and welfare of the fish.